The invention is based on a hydraulic device, e.g. on a hydraulic valve or a hydraulic pump, the hydraulic device having a nut part, e.g. a housing or a control piston, with a threaded hole which has an internal screw thread with a defined nominal diameter and with a defined, uniform pitch, and having a screw part, which has an external screw thread with the same nominal diameter as the threaded hole and with a defined, uniform pitch, which is screwed into the threaded hole.
It is known, for example from the journal “Industrieanzeiger”, Edition 83/88, pp. 24 to 25, to secure a screw part in a threaded hole by adhesive bonding. To do this, the threads have to be free of grease, dirt and moisture. In hydraulic devices, in which the screw part is very often a nozzle or a closure screw, which generally has to be exchanged or released and refitted from time to time, the measures required in order to secure the screw part used in an exchange of this type are very laborious, since it is difficult to keep the threads free of grease or to remove grease and hydraulic oil which have penetrated into the gap between the threads while the hydraulic device is operating. A further drawback is that when the screw part is being screwed into the threaded hole adhesive can flow away or be shaved off and passes into the hydraulic circuit in which the hydraulic device is located. This contaminates the hydraulic fluid which is used. Particularly if the screw part is a nozzle, there is a risk of the nozzle bore becoming blocked by applied adhesive. Overall, securing a screw by adhesive bonding is laborious, not a very reliable process and is also not clean.